1. Field of the Invention
The invention relates to the retrieval of suture anchors from a site of implantation in bone. More particularly, the invention relates to devices and methods for retrieving threaded suture anchors during either open or closed (endoscopic) surgical procedures.
2. Description of the Prior Art
In the course of certain surgical procedures, soft tissue is secured to a selected bone surface either directly, via some type of implant, or indirectly via an implant (i.e. an anchor) to which suture is attached, the suture then being tied to the soft tissue to hold it in place. Anchors may be used to attach soft tissue such as ligaments, tendons, muscles, etc. to a surface from which the soft tissue has become detached and may also be used to secure soft tissue to supplementary attachment sites for reinforcement. For example, in urological applications anchors may be used in bladder neck suspensions to attach a portion of the bladder to an adjacent bone surface. Such soft tissue attachment may be done during either open or closed surgical procedures, the latter being generally referred to as arthroscopic or endoscopic surgery. The terms "arthroscopic" and "endoscopic" may be used interchangeably herein and are intended to encompass arthroscopic, endoscopic, laparoscopic, hysteroscopic or any other similar surgical procedures performed with elongated instruments inserted through small openings in the body.
In procedures requiring suturing of soft tissue to bone, the suture is first anchored by so-called suture anchors to the bone before suturing of the soft tissue. The prior art includes numerous types of suture anchors adapted to be secured in the bone, sometimes directly in one step and sometimes in pre-drilled holes or tunnels. The term "suture anchor" is used broadly and will be understood to refer to devices having a similar structure even if material other than suture is connected to the device. Some prior art suture anchors are elongated and have annular ribs or radially extending barbs and are required to be pushed or hammered directly into bone or into a pre-formed bone tunnel (exemplified by U.S. Pat. Nos. 5,102,421 (Anspach, Jr.); 5,141,520 (Goble et al.); 5,100,417 (Cerier et al.); 5,224,946 (Hayhurst et al.) and 5,261,914 (Warren)). Pushing an anchor into place has the disadvantage of potential trauma and damage to surrounding bone tissue, and has limited applicability where the location of the bone tunnel or pre-drilled hole is not axially aligned with an arthroscopic portal to permit transmission of the impacting force through an impactor to the anchor. An impacted suture anchor is not easily removable without damaging the bone into which it has been placed. Consequently, threaded suture anchors are often used as exemplified by U.S. Pat. Nos. 5,156,616 (Meadows et al.) and 4,632,100 (Somers et al.). Depending upon the type of threaded anchor, the insertion procedure may enable direct threading of the anchor into the bone or it may sometimes require that a pilot hole first be drilled into the bone, the hole then either enabling an anchor to be screwed in or enabling threads to be tapped to receive the anchor.
In many instances, the suture anchor needs to be removed. For example, a particular implantation site may turn out to be unsuitable, either because of location or configuration, and the surgeon must either remove the anchor and place it elsewhere, or otherwise vary the procedure. Sometimes the anchor removal must occur after several months of healing so the anchor is overgrown with soft tissue and/or bone. With non-threaded prior art anchors there is no possibility of easily removing the inserted anchor and a second anchor must be inserted either in the same hole or a new hole. Accordingly, two (or possibly more) anchors may be left at the surgical site, only one of which is functional.
While threaded anchors are preferable in this regard because of the relative ease with which they may be removed from an implantation site, there is no known anchor retrieval device which facilitates the retrieval of a threaded anchor from an implantation site, particularly after several months of healing and bony ingrowth. Currently known removal procedures involve merely unscrewing a threaded anchor with the same screwdriver instrument used to implant it. However, even in endoscopic applications where the anchor is immediately removed after implantation, this is not as desirable as it sounds because once the anchor is removed from the bone it is not attached to the driver and may fall into the body cavity. The situation is even worse if the procedure is further complicated by removal after several months after implantation. Known methods for decorticating bone covering an anchor are relatively invasive and involve bone punches, picks, burrs, trephines, etc.
Many threaded suture anchors have a cylindrical threaded body with a drive portion at one end, the drive portion often having approximately the same diameter as the body. There is no "head" as one may find on some bone screws and this further limits the ease with which the anchor may be removed.
It is accordingly an object of this invention to provide a suture anchor retriever for removing a threaded suture anchor during an endoscopic surgical procedure.
It is further an object of this invention to provide a suture anchor retriever capable of removing a threaded anchor and holding it securely to facilitate its removal from the body through an access portal or cannula.
It is also an object of this invention to produce a suture anchor retriever capable of removing a threaded suture anchor from a site of implantation even after the anchor access may be somewhat obscured by soft tissue and/or bone. It is also an object to remove such a threaded suture anchor while minimizing and facilitating the removal of the surrounding bone.
It is another object of this invention to produce a suture anchor retriever capable of removing a threaded suture anchor having a headless, threaded cylindrical body.